A conventional bracket assembly for a rack is disclosed in U.S. Pat. No. 7,357,362, titled “Bracket Positioning Structure for a Slide” to Yang, and US Published Number 2003/0107309, titled “Dual Flat Springs for Tool-Less Slide Installation” to Lauchner. Lauchner discloses the use of two springs. The end of one spring leans on a frame of a rack. Yang discloses an arm having at least a toothed portion which is urged by a spring so as to engage with the frame.
The arm disclosed by Yang includes the toothed portion which is engaged with the frame, however, only the cross section of the toothed portion, a thickness of a board-like piece, is engaged with the frame. This can only provide a temporary positioning feature and the engagement is not strong enough especially when a heavy load is connected with the bracket.